<!doctype html>
<html>

<head>
    <meta charset="utf-8">
    <title>HTML5 canvas炫酷喜庆全屏烟花动画特效</title>

    <style>
        body {
            background: #000;
            margin: 0;
        }

        canvas {
            cursor: crosshair;
            display: block;
        }
    </style>

</head>

<body>

    <canvas id="canvas"></canvas>

    <script>
        // 在画布上设置动画时，最好使用requestAnimationFrame而不是setTimeout或setInterval
        // 但并非所有浏览器都支持，有时需要前缀，因此我们需要垫片
        window.requestAnimFrame = (function () {
            // 浏览器兼容写法
            // var requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame ||  window.webkitRequestAnimationFrame || window.msRequestAnimationFrame
            // var cancelAnimationFrame = window.cancelAnimationFrame || window.mozCancelAnimationFrame
            return window.requestAnimationFrame ||
                window.webkitRequestAnimationFrame ||
                window.mozRequestAnimationFrame ||
                function (callback) {
                    window.setTimeout(callback, 1000 / 60);
                };
        })();

        var canvas = document.getElementById('canvas'),
            ctx = canvas.getContext('2d'),
            cw = window.innerWidth,
            ch = window.innerHeight,
            fireworks = [],
            particles = [],
            hue = 120,
            limiterTotal = 5,
            limiterTick = 0,
            timerTotal = 80,
            timerTick = 0,
            mousedown = false,
            mx,
            my;

        canvas.width = cw;
        canvas.height = ch;


        function random(min, max) {
            return Math.random() * (max - min) + min;
        }

        function calculateDistance(p1x, p1y, p2x, p2y) {
            var xDistance = p1x - p2x,
                yDistance = p1y - p2y;
            return Math.sqrt(Math.pow(xDistance, 2) + Math.pow(yDistance, 2));
        }

        function Firework(sx, sy, tx, ty) {
            this.x = sx;
            this.y = sy;
            this.sx = sx;
            this.sy = sy;
            this.tx = tx;
            this.ty = ty;
            this.distanceToTarget = calculateDistance(sx, sy, tx, ty);
            this.distanceTraveled = 0;
            this.coordinates = [];
            this.coordinateCount = 3;
            while (this.coordinateCount--) {
                this.coordinates.push([this.x, this.y]);
            }
            this.angle = Math.atan2(ty - sy, tx - sx);
            this.speed = 2;
            this.acceleration = 1.05;
            this.brightness = random(50, 70);
            this.targetRadius = 1;
        }

        Firework.prototype.update = function (index) {
            this.coordinates.pop();
            this.coordinates.unshift([this.x, this.y]);

            if (this.targetRadius < 8) {
                this.targetRadius += 0.3;
            } else {
                this.targetRadius = 1;
            }

            this.speed *= this.acceleration;

            var vx = Math.cos(this.angle) * this.speed,
                vy = Math.sin(this.angle) * this.speed;
            this.distanceTraveled = calculateDistance(this.sx, this.sy, this.x + vx, this.y + vy);

            if (this.distanceTraveled >= this.distanceToTarget) {
                createParticles(this.tx, this.ty);
                fireworks.splice(index, 1);
            } else {
                this.x += vx;
                this.y += vy;
            }
        }

        Firework.prototype.draw = function () {
            ctx.beginPath();
            ctx.moveTo(this.coordinates[this.coordinates.length - 1][0], this.coordinates[this.coordinates.length - 1][1]);
            ctx.lineTo(this.x, this.y);
            ctx.strokeStyle = 'hsl(' + hue + ', 100%, ' + this.brightness + '%)';
            ctx.stroke();

            ctx.beginPath();
            ctx.arc(this.tx, this.ty, this.targetRadius, 0, Math.PI * 2);
            ctx.stroke();
        }

        function Particle(x, y) {
            this.x = x;
            this.y = y;
            this.coordinates = [];
            this.coordinateCount = 5;
            while (this.coordinateCount--) {
                this.coordinates.push([this.x, this.y]);
            }
            this.angle = random(0, Math.PI * 2);
            this.speed = random(1, 10);
            this.friction = 0.95;
            this.gravity = 1;
            this.hue = random(hue - 20, hue + 20);
            this.brightness = random(50, 80);
            this.alpha = 1;
            this.decay = random(0.015, 0.03);
        }

        Particle.prototype.update = function (index) {
            this.coordinates.pop();
            this.coordinates.unshift([this.x, this.y]);
            this.speed *= this.friction;
            this.x += Math.cos(this.angle) * this.speed;
            this.y += Math.sin(this.angle) * this.speed + this.gravity;
            this.alpha -= this.decay;

            if (this.alpha <= this.decay) {
                particles.splice(index, 1);
            }
        }



        Particle.prototype.draw = function () {

            ctx.beginPath();
            ctx.moveTo(this.coordinates[this.coordinates.length - 1][0], this.coordinates[this.coordinates.length - 1][1]);
            ctx.lineTo(this.x, this.y);
            ctx.strokeStyle = 'hsla(' + this.hue + ', 100%, ' + this.brightness + '%, ' + this.alpha + ')';
            ctx.stroke();


        }

        function createParticles(x, y) {
            var particleCount = 30;
            while (particleCount--) {
                particles.push(new Particle(x, y));
            }
        }

        function loop() {
            requestAnimFrame(loop);

            hue += 0.5;

            ctx.globalCompositeOperation = 'destination-out';
            ctx.fillStyle = 'rgba(0, 0, 0, 0.5)';
            ctx.fillRect(0, 0, cw, ch);
            ctx.globalCompositeOperation = 'lighter';

            var text = "新年快乐啊!!";
            ctx.font = "50px sans-serif";
            var textData = ctx.measureText(text);
            ctx.fillStyle = "rgba(" + parseInt(random(0, 255)) + "," + parseInt(random(0, 255)) + "," + parseInt(random(0, 255)) + ",0.3)";
            ctx.fillText(text, cw / 2 - textData.width / 2, ch / 2);

            var i = fireworks.length;
            while (i--) {
                fireworks[i].draw();
                fireworks[i].update(i);
            }

            var i = particles.length;
            while (i--) {
                particles[i].draw();
                particles[i].update(i);
            }

            if (timerTick >= timerTotal) {
                if (!mousedown) {


                    for (var h = 0; h < 50; h++) {
                        fireworks.push(new Firework(cw / 2, ch / 2, random(0, cw), random(0, ch)));
                    }


                    timerTick = 0;
                }
            } else {
                timerTick++;
            }

            if (limiterTick >= limiterTotal) {
                if (mousedown) {
                    fireworks.push(new Firework(cw / 2, ch / 2, mx, my));
                    limiterTick = 0;
                }
            } else {
                limiterTick++;
            }
        }

        canvas.addEventListener('mousemove', function (e) {
            mx = e.pageX - canvas.offsetLeft;
            my = e.pageY - canvas.offsetTop;
        });

        canvas.addEventListener('mousedown', function (e) {
            e.preventDefault();
            mousedown = true;
        });

        canvas.addEventListener('mouseup', function (e) {
            e.preventDefault();
            mousedown = false;
        });

        window.onload = loop;

    </script>
</body>

</html>